Environment: Plants costing $270 million may take 11 years to build. District seeks a shield from fines in the interim after it decides not to seek a waiver extension.

In the wake of a historic decision to begin more intensive treatment of local waste water, engineers at the Orange County Sanitation District began working in earnest Thursday on plans for two facilities estimated to cost $270 million and take as long as 11 years to build.

Attorneys for the Fountain Valley-based agency were also preparing for negotiations with state and federal authorities to shield it from penalties as it gives up its federal waiver allowing it to pump moderately treated sewage about four miles off Huntington Beach.

The district considered seeking a renewal of its waiver to the U.S. Clean Water Act until Wednesday night, when a campaign by environmental activists--concerned about repeated closures of polluted beaches--persuaded 13 of the district's 25 board members to vote to treat O.C. sewage to the same levels as nearly all of the nation's 16,000 other sanitation agencies.

More immediately, state water officials are scheduled to decide today whether to allow the district to chlorinate the 243 million gallons it discharges daily. Chlorination had been proposed earlier this year after a plume of the discharged sewage migrated back to within half a mile of Newport Beach.

"We've got work to do," said Blake Anderson, general manager of the sanitation agency, which serves more than 2.7 million residents and businesses in northern and central Orange County.

Environmentalists were euphoric Thursday. They had prevailed over some business leaders and local officials who contended that the cost of additional treatment was too great and its impact on coastal water quality unknown.

"This is a start," said Jan Vandersloot, founder of the Ocean Outfall Group, which conducted a city-by-city campaign to kill the waiver. "It's not ended; it's a very good beginning."

The higher standards will require building sewage treatment plants in Fountain Valley and Huntington Beach. Currently, only half the discharged waste water receives treatment to remove most microscopic solids and bacteria, viruses and other pathogens.

Initially, the district estimated greater treatment could cost as much as $400 million, but revised that figure downward this spring. Most residents would pay an average of $16 more annually for the new facilities; businesses could pay significantly more, depending on the amount of sewage generated.

The district is studying which technology to employ.

The conventional method involves bacteria, contained in sludge, that eat the solids and reduce the amount of oxygen used. "It's like billions and billions of little PacMen consuming the dissolved material in wastewater," Anderson said.

He said the district will explore micro-filtration and other techniques, and decide upon a method within two years. An independent panel of sanitary engineers will review the district's schedules and timelines, he said.

One fear that almost derailed the vote to abandon the waiver was raised late Wednesday by agency attorneys. They said that without a waiver in place once the current one expires next June, the district would be violating the federal Clean Water Act until the new facilities come on line about 2013. That could mean fines starting at $3,000 a day, lawyers said..

On Thursday, state and federal officials expressed optimism that all parties could reach an agreement that would shield the district from penalties.

"They're stepping up and doing the right thing," said Kurt Berchtold, assistant executive officer of the Santa Ana Regional Water Quality Control Board.